JPH04321879A - Rotary shaft lip seal - Google Patents

Abstract

PURPOSE: To provide a rotary shaft lip seal having an improved seal effect and extremely long service life. CONSTITUTION: This rotary shaft lip seal has a seal axis and a seal lip of polymeric material surrounding a shaft to be sealed, and the seal lip is demarcated on the inside by an inner surface that tapers out in the form of a hollow cone toward the side facing away from the sealed space. In the rotary shaft lip seal where ribs projecting radially inward distributed uniformly circumferentially on this inner surface, the ribs 3 consist of undulations propagated along the inner surface 2, 1 parallel with the circumference, the difference between the adjacent maximal and minimal intervals 4, 5 along the circumference between the inner surfaces 2, 1 and the seal axis 6 is less than 0.3 mm.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary shaft lip seal having a seal axis and a seal lip made of a polymeric material surrounding a shaft to be sealed.

0002

[Prior Art and Problems to be Solved] Such a rotary shaft lip seal is disclosed in German Patent Specification No. 115357.
Known by No. 8. There, arcuately configured ribs are arranged on the end face of the sealing lip, which together with a lip contact surface with ribs extending obliquely to the sealing axis act to feed the sealing medium in the direction of the sealed space. cause. However, in this case, it must be noted that the service life of the rotary shaft lip seal is not sufficient. The seal lip of a rotary shaft lip seal is subject to strong wear due to lack of lubrication during rotation of the sealed shaft. Therefore, as the period of use of the rotary shaft lip seal increases, the sealing result, especially when the shaft is stopped, becomes less satisfactory.

The present invention provides a rotary shaft lip seal of the above type, which has an improved sealing effect and a significantly longer service life, and which prevents liquid in the sealed space from leaking either when the shaft is stopped or when the shaft rotates. The purpose is to improve.

0004

[Means for Solving the Problems] According to the invention, this object has a sealing axis and a sealing lip made of a polymeric material surrounding a shaft to be sealed, the sealing lip being on the inside a space to be sealed. In a rotary shaft lip seal, the lip seal is limited by an inner surface that expands into a hollow conical shape as it moves away from the shaft, and has ribs distributed uniformly in the circumferential direction and projecting radially inward on this inner surface. This is achieved by a rotary shaft lip seal formed by a corrugation extending in the direction, and characterized in that the difference between the maximum and minimum circumferentially adjacent distances between the inner surface and the seal axis is less than 0.3 mm. The dependent claims relate to advantageous configurations.

[0005] In the rotary shaft lip seal according to the present invention, the rib is formed by a corrugated shape extending in the circumferential direction of the inner surface, and the difference between the maximum distance and the minimum distance between the inner surface and the seal axis in the circumferential direction is 0.3 mm. It has been made smaller. Advantageously in this case, the corrugated inner surface has its radially inwardly directed ribs resting against the shaft under preload and its radially outwardly directed ribs just touching the surface of the shaft or having a small distance therefrom; The inner surface achieves an axial supply and discharge action in the direction of the sealed space. The inventive configuration of the rotary shaft lip seal provides excellent lubrication between the sealing lip and the adjacent shaft, which results in very little wear on the sealing surfaces and a very long service life due to a constant and good sealing effect. Become. The degree of supply and discharge action depends on the inclination angle of the sealing lip. Furthermore, advantageously, the rotary shaft lip seal of the present invention not only seals the liquid-filled space from the surroundings, but also allows the liquid to be sent into the sealed space through the side of the seal lip due to the supply/discharge action of the rotary shaft lip seal. The liquid is then retained within this space once the feeding process has been completed. Due to the various distances between the inner surface and the sealing axis, the medium to be sealed is entrained during rotation of the shaft and is always transported back into the space to be sealed. Even when the shaft is stopped, the gap between the shaft and the sealing surface is extremely small, so the medium does not advance.

This behavior depends on certain external conditions, such as the configuration of the inner surface, the distance between the inner surface and the seal axis, the width of the seal lip,
It depends on the angle of the seal lip with respect to the seal axis. Furthermore, the elastomer value of the rotary shaft lip seal and the radial forces applied to it influence its function. It is generally noted that the difference between the circumferentially adjacent maximum and minimum distances between the inner surface and the seal axis is preferably 0.3 m.
It can be made smaller than m.

The inner surface can be formed by a conical surface that is continuous in the circumferential direction of the assumed cone, and this conical surface alternates between a conical axis located on the radially inner side of the sealing lip and a conical axis located on the radially outer side of the sealing lip. have The uniform curvature of the conical surface results in an even distribution of the medium to be sealed back into the space to be sealed. Furthermore, uniformly structured conical surfaces can advantageously be manufactured simply and economically.

[0008] The inner surface can be formed in a sinusoidal waveform in the circumferential direction. Different slopes along the sinusoidal curve result in feeding effects of different strengths in different regions of the sealing lip. The configuration of the sinusoidal inner surface allows the rotary shaft lip seal to adapt particularly well to different viscosities of the sealing medium.

The difference between the circumferentially adjacent maximum and minimum distances between the inner surface and the seal axis may be less than 0.15 mm, preferably less than 0.1 mm. The smaller the difference in distance between the corrugated inner surface and the sealing axis, the greater the feeding effect in the direction of the space to be sealed. As the difference in distance becomes smaller, the sealing effect becomes stronger, and 0.
Differences of less than 1 mm are preferably applied for sealing liquid media. Large differences of the order of 0.1 mm to 0.3 mm can be produced economically and are suitable for sealing viscous media.

Depending on various parameters, a rotary shaft lip seal adapted to the particular application is obtained when the inner surface has a circumferential length between adjacent peaks of the corrugations of at least 1.5 mm. A circumferential length of at least 1.5 mm between wave crests applies in particular to rotary shaft lip seals with relatively small internal diameters.

The rotary shaft lip seal for sealing large diameter shafts may have an inner surface having a circumferential length of at least 5 mm between adjacent peaks of the corrugations. At least 2 regardless of the circumferential length between adjacent vertices
Two complete corrugations can be placed along the inner surface. As the circumferential length increases, the angle formed by the concave surface of the corrugation and the adjacent convex surface becomes smaller, which makes it possible to achieve a good sealing, especially when the shaft is stationary, and to keep the sealing medium from flowing into the sealed space when the shaft rotates. The effect of sending it back inside is also improved.

[0012] The inner surface may have an axial length of at least 1 mm. Advantageously, a good static and dynamic sealing of the shaft and a low load on the inner surface of the rotary shaft lip seal are ensured here. If the axial length of the inner surface is at least 1 mm, the service life will be significantly longer, since the specific load on the sealing surface will be lower.

The inner surface can be bounded on both axial sides by end faces perpendicular to the sealing axis. With this advantageous configuration, a precisely defined loading of the inner surface in the radial direction towards the shaft can be achieved. Furthermore, the manufacturability of the inner surface, which is defined on both axial sides by end faces perpendicular to the sealing axis, is essentially facilitated.

[0014] The inner surface may be at an angle of 3 to 20° to the sealing axis on the side opposite the sealed space with respect to the sealing lip. Depending in particular on the medium to be sealed and on the circumferential speed of the shaft, the supply/discharge action and the sealing function can be adapted to the particular conditions of the application in question.

A particularly advantageous effect with respect to the function of the rotary shaft lip seal and its service life is that the inner surface of the sealing lip is located at 3° relative to the sealing axis on the side opposite the sealed space.
．． Obtained when forming an angle of 123° to 3.875°.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The object of the present invention will be further explained below with reference to the accompanying drawings. FIG. 1 shows the main part of a rotary shaft lip seal with a seal axis 6, which surrounds the shaft to be sealed 1 with a sealing lip 2 made of polymeric material. The sealing lip 2 is delimited on the inside by an inner surface 2.1 which expands into a hollow conical shape away from the space to be sealed 8. The inner surface 2.1 of the sealing lip 2 is shown in the area of the largest elevation on the shaft 1. Inner surface 2.1
The relatively long axial length of ensures a good static sealing of the space to be sealed by capillary action. When the shaft 1 rotates, the corrugated inner surface 2.1 of the sealing lip 2 produces a feeding effect in the direction of the space to be sealed 8. FIG. 1 shows the maximum distance 4 between the inner surface 2.1 and the seal axis 6. The inner surface 2.1, on its side opposite the sealed space 8, forms an angle 9 with respect to the sealing axis 6, which angle can generally be between 3 and 20 DEG, here approximately 6 DEG.

FIG. 2 shows the same rotary shaft lip seal as in FIG. 1, but in cross section at a convex portion of the circumferential surface. The minimum distance 5 between the inner surface 2.1 and the sealing axis 6 is shown in this figure. The inner surface 2.1 rests against the shaft 1 under preload in this area. In this case too, the angle 9 between the inner surface 2.1 and the sealing axis 6 is approximately 6°.

FIG. 3 shows the rotary shaft lip seal of FIGS. 1 and 2 in a front view. The maximum distance 4 and the minimum distance 5 between the inner surface 2.1 and the sealing axis 6 are shown on an enlarged scale in order to clarify the mode of action. The inner surface 2.1 is sinusoidally corrugated in the circumferential direction and has a circumferential length of 7 between adjacent peaks of the corrugations. Regardless of the size of the rotary shaft lip seal, at least two complete corrugations, each having a circumferential length of 7, are required along the inner circumference of the rotary shaft lip seal.

In FIG. 4, as in FIG. 1, the sealing lip 2 is shown at a maximum distance 4 relative to the sealing axis 6. In this case too, the inner surface 2.1 does not come into contact with the shaft 1. The inner surface 2.1 of the sealing lip 2 is shown schematically on a significantly enlarged scale and, in a highly functional implementation, has an axial length of at least 1 mm. The inner surface 2.1 is axially bounded by end faces 2.2, 2.3 perpendicular to the sealing axis 6. The vertically extending end faces provide a strictly limited load on the inner surface 2.1 in the radial direction.

In FIG. 5, the sealing lip shown in FIG. 4 is shown at a minimum distance 5 from the sealing axis 6. The sealing lip rests against the surface of the shaft 1, also under preload, as shown in FIG.

[0021]

Effects of the Invention In the rotary shaft lip seal of the present invention, the radially inward ribs on the corrugated inner surface abut against the shaft under preload, and the radially outward ribs just touch or slightly touch the surface of the shaft. This inner surface achieves an axial supply and discharge action in the direction of the sealed space. This provides excellent lubrication between the sealing lip and the shaft, resulting in a rotary shaft lip seal with a consistently good sealing effect and an extremely long service life.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged view of a seal lip of a rotary shaft lip seal according to the present invention, taken along the line AA in FIG. 3;

FIG. 2 is a partially enlarged view of the seal lip of the rotary shaft lip seal according to the present invention, taken along the line BB in FIG. 3;

FIG. 3 is a front view of the rotary shaft lip seal.

FIG. 4 is an enlarged cross-sectional view of the seal lip of another embodiment of the rotary shaft lip seal taken at the maximum distance;

FIG. 5 is an enlarged cross-sectional view of the seal lip of the rotary shaft lip seal taken along the minimum distance.

[Explanation of symbols]

1 Shaft 2 Seal lip 2.1 Inner surface 3 Ribs 6 Seal axis 8 Space

Claims (11)

[Claims] Claim 1: A seal having a seal axis and a seal lip made of a polymeric material surrounding a shaft to be sealed, the seal lip being limited on the inside by an inner surface that expands into a hollow conical shape as it moves away from a space to be sealed. In a rotary shaft lip seal in which ribs are arranged on the inner surface in the circumferential direction and protrude radially inward, the ribs (3) have a corrugated shape extending in the circumferential direction of the inner surface (2.1). A rotary rotary, characterized in that the difference between the maximum distance (4) and the minimum distance (5) adjacent in the circumferential direction between the inner surface (2.1) and the seal axis (6) is less than 0.3 mm. Shaft lip seal. [Claim 2] The inner surface (2.1) is formed by a conical surface that is continuous in the circumferential direction of the assumed cone, and this conical surface is in contact with the conical axis located radially inside the sealing lip (2) and radially outside. 2. The rotary shaft lip seal of claim 1, wherein the rotary shaft lip seal has a conical shaft alternating with a certain conical shaft. 3. Rotary shaft lip seal according to claim 1, characterized in that the inner surface (2.1) is sinusoidally shaped in the circumferential direction. [Claim 4] Inner surface (2.1) and seal axis (6)
The maximum distance (4) and minimum distance (4) adjacent to each other in the circumferential direction are
5) The rotary shaft lip seal according to any one of claims 1 to 3, wherein the difference between the rotary shaft lip seal and the rotary shaft lip seal is smaller than 0.15 mm. [Claim 5] Inner surface (2.1) and seal axis (6)
The maximum distance (4) and minimum distance (4) adjacent to each other in the circumferential direction are
5) The rotary shaft lip seal according to any one of claims 1 to 3, wherein the difference between the lip seal and the rotary shaft lip seal is less than 0.1 mm. 6. The inner surface (2.1) is corrugated and has a circumferential length (7) of at least 1.5 mm between adjacent peaks.
The rotary shaft lip seal according to any one of claims 1 to 5, characterized in that it has: 7. The inner surface (2.1) according to claim 1, wherein the inner surface (2.1) has a circumferential length (7) of at least 5 mm between adjacent peaks of the corrugation. Rotary shaft lip seal. [Claim 8] The inner surface (2.1) is at least 1 mm.
A rotary shaft lip seal according to any one of claims 1 to 7, characterized in that it has an axial length of . 9. Claims 1 to 8 characterized in that the inner surface (2.1) is delimited on both axial sides by end faces (2.2, 2.3) perpendicular to the sealing axis (6). The rotary shaft lip seal according to any one of the above. [Claim 10] The inner surface (2.1) has a seal lip (
10. The rotary according to claim 1, characterized in that, with respect to 2), it forms an angle (9) of 3 to 20° with respect to the seal axis (6) on the side opposite to the sealed space (8). Shaft lip seal. [Claim 11] The inner surface (2.1) has a seal lip (
2) forming an angle (9) of 3.123° to 3.875° with respect to the seal axis (6) on the side opposite to the sealed space (8). Rotary shaft lip seal as described in section.